Motor fuel



April 30, 1940. M. HULL MOTOR lFUEL.

Filed Deo. 31, '1937 Patented Apr. 30, 1940 UNITED STATE-.s

PATENT OFFICE MOTOR FUEL Carl Max Hull, Chicago, lll., aligner toStandgd Oil Company, Chicago, lll., a corporation of applicationDecember 31, 1937, serial Nn. mm n claims. (ci. iss-1o) This inventionrelates to a process of producing motor fuels and particularly motorfuels of the type of gasoline from hydrocarbon gases, more particularlythe butanes and butylenes. In the cracking of petroleum oils to producegasoline there is produced a mixture of hydrocarbon gases from which maybe conveniently separated a propane fraction and a butane fraction. Thebutane fraction contains a mixture of the normal and isobutane and thethree butylenes, i. e., lbutene, 2-butene and isobutylene. The object ofthe present invention is to convert this gas fraction hereinafterreferred to as the C4 hydrocarbons into valuable motor fuel. Anotherobject of the invention is to produce a high octane motor fuel from theC4 hydrocarbons in higher yield than heretofore has been produced fromthis material. Still another object of the invention is to process amixture of the C4 hydrocarbons in a novel manner whereby they areconverted into certain polymerization products with a chemical structurewhich confers upon them high antidetonating properties instead of theproducts heretofore produced having undesirable chemical structuregiving low anti-detonating characteristics. Other objects of theinvention will be apparent from the following description.

It has been known heretofore that a mixture of butylenes can bepolymerized by catalysts under various conditions of heating to yield amotor fuel having an antiknock value of about octane number. It has alsobeen known that isobutylene can be polymerized to produce diisobutyleneor so-called iso-octene having a high antiknock value and that theiso-octene can be hydrogenated to produce iso-octane having ananti-knock value of about octane number.

Referring to the drawing, a stream' of C4 hydrocarbons is introducedunder pressure by line III to heater 5I where the temperature is raisedto about 250 to 350 F. The hydrocarbon stream is then passed intocatalyst chamber I2 containing a suitable polymerization catalyst wherethe pressure is suitably maintained at about 250- '750 1b./sq. in.,preferably atvabout 500 lb./sq. in. For this purpose I prefer to employphosphoric acid on silica or on various silicates such as infusorialearth. Before introducing the feed into the polymerizer I2, however, Imay add an additional amount of isobutylene by line I3 to make theconcentration of isobutylene equal to or greater than the concentrationof 2-butene in the C4 fraction in case there is a deficiency ofisobutylene. I may also add a small carefully regulated amount of steamto the hydrocarbons before introducing them into polymerizer- I2 inorder to increase the life oi' the catalyst and to improve the qualityof the product. The conditions maintained in polymerizer I2 are suchwith vrespect to catalyst, temperature and time of reac- 5 tion as topermit the l-butene to pass through substantially unchanged.

In ordinary commercially available C4 hydrocarbon mixtures, theconcentration of 2-butene will usually be about 5 to 20%. lI have found10 that if isobutylene is present in an equi-molecular amount with the2-butene, these hydrocarbons polymerize together under the conditionsdescribed, to produce a co-polymer or octene which, on laterhydrogenation, is characterized 16 by a high knock rating only slightlyless than that of iso-octane derived entirely from iso-butylene. By thismethod of copolymerization of the 2-butene I am therefore enabled'toproduce a motor fuel of outstanding knock rating, 20 whereas thepolymerization of the Z-butene alone produces a motor fuel of onlyintermediate value with respect to antiknock characteristics.

The reaction mixture from I2 is conducted by line I4 to fractionator I5wherein C4. hydrog5 carbons are removed as a vapor and thepolymerization products, comprised principally of dibutylenes arewithdrawn by line I6. The C4 hydrocarbons are conducted by line I'I tofractionator I8 where they are further fractionated to 30 separate theminto an isobutane fraction (containing most of the l-butene) which iswithdrawn as a vapor by line I9, and a normal butane fraction, withdrawnby line 20. Higher boiling hydrocarbons which may be present are removed35 by line 2I. Normal butane, which may be contaminated with a smallamount of l-butene is conducted by line 20 to scrubber 20a where the 1-butene is absorbed by a suitable reagent such as sulfuric acid. Theabsorption product may be 40 utilized in a sulfuric acid polymerizationprocess or, by hydrolysis, may be converted into secondary butylalcohol. Where the amount of contaminating l-butene is very small, I maybypass scrubber 20a by line 20h. The normal bu- 45 tane stream is thenled by line 20c to isomerizer 22 where it is held in contact in liqueiedform with a suitable isomerizing catalyst at a mild temperature, forexample about to 200 F. The catalyst may be anhydrous aluminum chlo- 50ride, aluminum bromide, aluminum chloride promoted with boron chloride,or aluminum chloride activated by a trace of moisture, by HCl or byother activating halides, e. g., CCl4, ethylene dichloride, etc. Underthe action of these catalysts u and under these mild temperatureconditions, for example 10o-300 F., the normal butane is converted intoisobutane to a large extent, for example 50-80%. Any 1butene which maybe present is partly polymerized and partly converted into 2-buteneunder these conditions. After treating to remove the catalyst, forexample, by ltration or by distillation and/or by washing with water,the reaction product is returned by line 23 to tower I8 wherebyisobutane formed in isomerizer 22 is separated and any unchanged normalbutane is recycled to the isomerizer 22.

The isobutane Withdrawn by line I9 is -conducted through heater 24wherein it is heated to a relatively high temperature, for example about8001000 F., and treated with a suitable dehydrogenating catalyst indehydrogenator 25. It chromium oxide is employed as the catalyst thetemperature may be maintained at about 900 to 925 F. The products,consisting principally of isobutylene and hydrogen with some unchangedisobutane and some degradation products, are

withdrawn by line 26 leading to fractionator 21 where hydrogen isseparated by line 28 and liquid isobutylene is removed by line I3.Isobutylene which tends to be carried away in line 28 with the hydrogenand degradation products such as ethane and propane may be recovered byintroducing an absorber oil in the top of tower 21. In the event that anabsorber oil is used, the absorbed product is subsequently separatedfrom the rich absorbent oil, fractionated by suitable means (not shown)and the isobutylene recovered therefrom is returned to feed line I3.

Isobutylene may be conducted by line I3 back to heater II as previouslydescribed, the amount introduced being suflicient to increase theconcentration of isobutylene in line I above that oi.' the 2-buteneconcentration therein. Excess isobutylene may be withmdrawn by valvedline 29 for various other uses; for example, it may be polymerized witha suitable catalyst to produce pure iso-octene which may then behydrogenated'to produce iso-octane motor fuel, especially valuablefor'aviation engines. The isobutylene may also be employed for themanufacture of resins, for example by treatment in the liquid phase withboron uoride at low temperatures of the order of 0 to 100 F. If desired,isobutylene from other sources, such asthe dehydration of isobutylalcohol, may be introduced into the system by line 30 in any amount.Similarly, in the case where isobutane is available from other sources,such as from the treatment of petroleum naphthas with aluminum chloride,it may be introduced into the 'system by valved line 3l.

Hydrogen which is derived from the fractionator 21 and may containsubstantial amounts of lower hydrocarbons is conducted by line 28 toheater l32 wherein it is mixed with thepolymers from lines I6 and/or 2|.'Ihe polymers are hydrogenated by suitable means in hydrogenator 33- forexample, in heater 32 the temperature of the polymers and hydrogen maybe raised to about 30G-500 F.A and the heated products introduced intohydrogenation catalyst l chamber 33 where they are brought into contactwith a suitable catalyst such as metallic nickel or nickel oxide. Theproducts are then conducted by line 34 into fractionator 35 where thehydrogenated products, consisting primarily of octanes, are withdrawn byline 36 as a high knock rating motor fuel having a knock rating of about90-9'1 octane number. Any excess hydrogen and uncondensed gases,including propane and lighter hydrocarbon gases, are withdrawn by line81. Heavier products undesired in the motor fuel are withdrawn by line38 and may be employed as charging stock for a cranking process orrefined to produce lubricating oil and other petroleum products.

As a modication of the foregoing process I may remove the l-butene fromthe gases withdrawn at the top of fractionator I by conducting themthrough valved line 40 to isomerizer 4I wherein the gases are contactedwith an acid catalyst. such as a phosphoric acid-silicate catalyst inthe presence of a small amount of steam if desired, at a temperature ofabout 500-600 F., -for example 550 F. Under these conditions thel-butene is converted substantially into 2-butene and some isobutylene.'I'he isomerized mixture is then conducted by line 42 to polymerizer 43,additional isobutylene -being introduced by line 44 to bring theconcentration of isobutylene in the mixture up to that of the 2-butene.Co-polymerization is effected in polymerizer 43, employing a suitablecatalyst, for example phosphoric acid at about 250 to 350 F., theconditions being substantially the same as in polymerizer I2.Polymerization products are then conducted by lines 45 and I1 leading tofractionator I8 where the polymers are separated and removed by line 2Ias hereinbefore described. In this modication of my process, I am ableto obtain a higher ultimate yield of polymers. Furthermore the amount of1butene introduced into fractionator I8 is reduced to a minimum and thefractionation is thereby simplified.

In another modification of my process I may eliminate fractionator I8and isomerizer 22 by closing valves 46 and 41 and opening valve 48 inline 49, thus diverting the gases from fractionator I5 to line 49 fromwhence they are conducted to condenser 49a and thence to scrubber 49h toremove oleilns as previously described with scrubber 20a. Thehydrocarbon stream is then led to isomerizer 50 which is operated undersubstantially the same conditions, with the same catalysts as describedfor use in isomerizer 22. Normal butane is converted to an appreciableextent into isobutane by the catalyst in 50 and the resulting productsare conducted by line 5I to heater 24 and thence to dehydrogenator 25,as

hereinbefore described. With this modification some simplication of theprocess and apparatus is effected, but at the cost of having to processa mixture of butanes in dehydrogenator 25 with resulting lowerefficiency and with the production of a butylene gas containing amixture of butylenes less valuable for special process such aslubricating oil synthesis and for the production of isobutene of highpurity.

` use polymerization catalysts for converting substantially all olens inthe gas introduced through line I1 into high boiling polymers which maybe withdrawn from the base of fractionator I8 by line 2 I. As examplesof such vigorous polymerizing catalysts I may mention aluminum chloride,sodium aluminum chloride (NaAlCli),

arcaica Also, it should vbe understood that where the C4 hydrocarbonsare treated in the liquid phase, pumps may be supplied to providesuiiicient pressure for the purpose, pressures of about 50 to 500 lbs.being sometimes required, depending on the temperature. simplified formfor clarity, but it should be understood that various details may besupplied without departing .from the spirit of my invention.

Having thus described my process, what I claim is:

1. 'I'he process o! converting a gas mixture of C4 hydrocarbonscontaining 1butene, 2butene, and normal butane into higher boilinghydrocarbons suitable for motor fuel and characterized by a high knockrating, which comprises adjusting the butylene composition of said C4hydrocarbon mixture to provide a concentration of isobutylene equal toor greater than the concentration of 2butene in the mixture, subjectingthe adjusted mixture of C4 hydrocarbons to the action of a polymerizingcatalyst under conditions whereat isobutylene and 2butene aresubstantially co-polymerized and l-butene present in the mixture issubstantially unaected, separating the resulting polymers from the gasmixture, treating the unreacted gas mixture in the liquid phase with anisomerizing catalyst under mild temperature conditions and therebysubstantially converting normal butane to isobutane, subjecting theisomerized gas mixture to the action of a dehydrogenating catalyst atelevated temperature whereby isobutane contained therein is substantially converted to isobutylene and hydrogen and recycling theisobutylene thus obtained to the original C4 hydrocarbon mixture toadjust the ratio of isobutylene to 2butene contained therein.

2. The process of claim 1 wherein hydrogen obtained from thedehydrogenation of isobutane is combined with the polymer resulting fromthe co-polymerization of isobutylene and 2butene to produce asubstantially saturated motor fuel of high knock rating 3. The processof converting a gas mixture containing normal butane and the threebutenes into motor fuel of high knock rating which comprises selectivelyco-polymerizing, by means of a catalyst, the isobutylene and 2butene insaid mixture substantially without polymerizing the l-butene, saidpolymerization of isobutylene and 2butene being regulated to produceprincipally octenes, subjecting the unpolymerized hydrocarbons,including l-butene, to the action of an olefin isomerizing catalystwhereby said l-butene is substantially converted to 2butene andisobutylene, adding an additional amount of isobutylene suiiicient tomake the concentration substantially equal the amount of 2butene in saidisomerized hydrocarbon mixture and subjecting the gases to a secondselective polymerizing operation whereby the isobutylene and 2- buteneare co-polymerized principally to octenes, subjecting the remainingsubstantially saturated unpolymerized hydrocarbons to the action of aparain isomerizing catalyst whereby a substantial amount'of the normalbutane is converted to The process has been described inl isobutane,dehydrogenating the resulting isobutane and unconverted normal butanewhereby a substantial amount'o! isobutylene is produced andrecycling'said isobutylene to one yoi! said polymerizing operationspreviously described.

4. The process of claim 3 wherein octenes produced in saidpolymerization operations are con- 'verted to octanes by subsequenthydrogenation.

5. The process of claim'3 wherein the polymerization catalyst isphosphoric acid maintained at about 250 to 350 F., the oleilnisomerizing catalyst is also phosphoric acid maintained at a temperatureof about 500 to 600 F. and the paraffin isomerizing catalyst is aFriedel-Crafts catalyst such as aluminum chloride.

6. The process of converting a gas mixture containing normal andisobutane and the three butenes into motor `fuel of high knock ratingwhich comprises selectively co-polymerizing, by means of a catalyst, theisobutylene and 2butene in said mixture substantially withoutpolymerizingl the l-butene, said polymerization of isobutyleneandZ-butene being regulated to produce principally octenes, subjectingthe unpolymerized hydrocarbons, including 1butene, to the action of anolen isomerizing catalyst whereby said 1- butene is substantiallyconverted to 2butene, adding an amount of isobutylene to increase theconcentration to substantially that of the 2- butene in said isomerizedhydrocarbon mixture and subjecting the gases to a second selectivepolymerizing operation whereby the butenes are converted principally tooctenes, subjecting the remaining unpolymerized hydrocarbons, consist-Aing principally of normal butane and isobutane, to fractionation,removing the isobutane as a distillate, withdrawing the normal butane asa reiiux liquidand subjecting it to the actionv of a paramn isomerizingcatalyst whereby it is converted substantially to isobutane, returningthe converted butane-isobutane mixture to said fractionating operationwhence isobutane is removed and unconverted normal butane is recycled tosaid paraiiin isomerizing operation, dehydrogenating said isobutanefraction to produce isobutylene and recycling said isobutylene to one ofsaid polymerizing operations previously described.

7. The process of claim 6 wherein octenes produced in said polymerizingoperations are converted to octanes by the action of hydrogen withdrawnfrom said dehydrogenating operation.

8. The process of converting a gas mixture of C4 hydrocarbons containingbutanes and buteneJs into higherboiling hydrocarbons suitable for motorfuel and characterized by a high knock rating, which comprises adjustingthe butylene composition of said C4 hydrocarbon mixture to provide aconcentration of isobutylene equal to or greater than the concentrationof 2butene in the mixture, subjecting the adjusted mixture of C4hydrocarbons to the action of a polymerizing catalyst under conditionswhereat isobutylene and 2butene are substantially co-polymerized and1-butene present in the mixture is substantially unaffected, separatingthe resulting polymers from the gas mixture, treating the gas mixture inthe presence of an acid acting catalyst whereby .the l-butene containedtherein is substantially isomerized to 2butene and iso-butylenecopolymerizing the 2butene in the mixture with an equal or greateramount of isobutylene added thereto, separating the resulting polymersfrom the gas mixture, treating the gas mixture in the liquid phase withan isomerizing catalyst under mild temperature conditions and therebysubstantialiy converting n-butane to isobutane, subjecting theisomerized gas mixture to the action o1' a dehydrogenating catalyst atelevated temperature whereby isobutane contained therein issubstantially converted to isobutylene and hydrogen and recycling theisobutylene thus obtained to said hydrocarbon gas mixtures to bepolymerized in order to adjust the ratio of isobutylene to 2 butenecontained therein.

9. In the conversion of an unsaturated C4 fraction of lhydrocarbonscontaining all three butenes in substantial amounts, into high knockrating motor fuels within the gasoline boiling range, the improvementcomprisin'g adjusting the olen composition of said hydrocarbon fractionto obtain an isobutylene concentration at least equal to theconcentration of normal 2butene in said C4 hydrocarbon fraction andsubsequently subjecting said olen mixture to polymerization in thepresence of an acid acting catalyst at a temperature above 250 F.whereby isobutylene and 2butene are copolymerized to produce motor fueloctenes substantially without affecting 1butene present in saidunsaturated C4 traction and separating said octenes from unpolymerizedC4 hydrocarbons.

10. The process of claim 9 wherein the catalyst is phosphoric aciddisposed on a suitable solid supporting material.

11. The process of claim 9 wherein the said C4 fraction contains anexcess of 2butene over isobutylene and the concentration of isobutylenein said unsaturated C4 hydrocarbon fraction is adjusted by addingextraneous isobutylene thereto.

CARLMAXHULL.

